Cirolana Leach, 1818

Bruce, Niel L. & Rodcharoen, Eknarin, 2023, Electrolana Schädel, Hyžný & Haug, 2021 (Crustacea: Isopoda: Cirolanidae), a Junior Synonym of Cirolana Leach, 1818 and a New Species of Metacirolana Kussakin, 1978 from Cretaceous Amber of Myanmar, Records of the Australian Museum (Rec. Aust. Mus.) 75 (4), pp. 405-412 : 406-407

Genus Cirolana Leach, 1818

Restricted synonymy:

Cirolana . —Bruce 1986: 139.— Brusca et al., 1995: 17.— Hyzny et al., 2013: 621.

Obtusotelson Schädel, van Eldijk, Winkelhorst, Reumer & Haug, 2020: 150 [type species Obtusotelson summesbergeri Schädel, van Eldijk, Vinkelhorst , Reumer & Haug, 2020; by monotypy].

Electrolana Schädel, Hyžny & Haug, 2021: 21 [type species Electrolana madelinae Schädel, Hyžny & Haug, 2021; by monotypy] (part, holotype only), new synonymy.

Remarks. The genera of Cirolanidae can be placed into three major divisions, formalized, and diagnosed by Kensley & Schotte (1989) as the subfamilies Cirolaninae Dana, 1852, Eurydicinae Stebbing, 1904 and Conilerinae Kensley & Schotte, 1989.

The holotype of Electrolana madelinae can be excluded from the Eurydicinae by having the following character states: frontal lamina sessile, broad, ventrally flat; clypeus ventrally flat, lacking any form of ventral blade; pereopods robust, ambulatory; pleonite 5 laterally enclosed by pleonite 4 and pleonite 3 posteriorly produced, overlapping pleonite 4. Further support for exclusion from the Eurydicinae is found in pereonite 1 in C. madelinae being longer than pereonite 2, and the pleon is 19% of total body length, whereas in the Eurydicinae pereonite 1 is not or only slightly longer than pereonite 2 and the pleon is usually in the range of 21–30% total body length.

Electrolana madelinae can be excluded from the Conilerinae on the basis of the pereopod morphology, primarily having simple ambulatory pereopods, lacking the produced superodistal angles of the ischium and merus of pereopods 1–3, lacking elongate acute robust setae and lacking the long setae present on all or the posterior pereopods and the expanded articles on the posterior pereopods as seen in genera such as Natatolana Bruce 1981 (see Keable, 2006) and Politolana Bruce, 1981 (see Riseman & Brusca, 2002); further, the proportions of the antennal peduncle differ, those of the Conilerinae having articles 3 and 4 about subequal in length and shorter than article 5, whereas Cirolaninae have antennal peduncle articles 1–3 short and 4 and 5 longest.

The antennular and antennal peduncle morphology of the holotype of Electrolana madelinae further identifies it as or close to Cirolana , in particular peduncle articles 1–3 short, article 4 and 5 long, rather than article 1 and 2 short, 3 and 4 long and subequal in length and article 5 longest (see Bruce, 1981, 1986; Riseman & Brusca, 2002), which is the state for genera such as Natatolana and Politolana (i.e. “Conilerinae”).

Electrolana madelinae has robust pereopods with a short dactylus, and sparse setae; the robust setae are comparatively short, and as such the pereopods are typical of the genus Cirolana . Genera such as Aatolana Bruce, 1993 (Keable, 1998), Baharilana Bruce & Svavarsson, 2003 ( Schotte & Kensley, 2005; Khalaji-Pirbalouty et al., 2015) and Odysseylana Malyutina, 1995 (see Sidabalok & Bruce, 2015) all differ in having the posterior pereopod articles either flattened or distally expanded (among other characters). The more similar Neocirolana Hale, 1925 differs primarily from Cirolana in having a narrow mandible as well as other mouthpart reductions ( Bruce & Hughes, 2020). Neocirolana is excluded, as, in all cases, the relative width of the head is narrower than in other genera of Cirolanidae . As the type species of Electrolana agrees with all of the visible comparable character states for species included in the genus Cirolana , both extant (see Bruce, 1986; Brusca et al., 1995; Kensley & Schotte, 1989; Schotte & Kensley, 2005) and fossil (Hyžný et al., 2013; Bruce et al., 2021), the genus Electrolana Schädel, Hyžny & Haug, 2021 is here placed into junior synonymy with Cirolana Leach, 1818 .

Brunneaga Polz, 2005 was originally placed in the Aegidae , and was transferred to the Cirolanidae by Wilson et al. (2011). Although described in detail from excellent material, B. tomhurleyi Wilson in Wilson, Paterson & Kear, 2011, however, it is incorrectly placed in Brunnaega . In Brunnaega all pleonites are laterally free and not overlapped by the preceding segment, as seen for example in Eurydice and most species of Metacirolana . Brunnaega tomhurleyi has pleonite 5 laterally enclosed by pleonite 4 and pleonite 3 ( Wilson et al., 2011: fig. 5) is also strongly posteriorly produced. Pleon morphology is highly consistent in cirolanid genera, and the difference in pleon shown between the type species Brunnaega roeperi Polz, 2005 and B. tomhurleyi is of generic merit. Without some pereopodal characters it is not possible to definitively place B. tomhurleyi into a genus, but as no characters exclude the species from Cirolana it is here tentatively placed in the combination Cirolana tomhurleyi (Wilson in Wilson, Paterson & Kear, 2011) comb. nov., pending discovery of more material.